CriticalCVE-2021-20028

    SonicWall Secure Remote Access (SRA) SQL Injection Vulnerability (CVE-2021-20028)

    Published In CISA KEV since Sources: CVE.org

    What is affected, what to do

    Improper neutralization of a SQL Command leading to SQL Injection vulnerability impacting end-of-life Secure Remote Access (SRA) products, specifically the SRA appliances running all 8.x firmware and 9.0.0.9-26sv or earlier

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • SonicWall SRA/SMA100 eq 8.x firmware..8.x firmware
    • SonicWall SRA/SMA100 eq 9.0.0.9-26sv and earlier...9.0.0.9-26sv and earlier.

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: CVE.org

    30.1 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 98.2

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    251.15 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploited
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

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    30.1 %
    Elevated — model estimates 10-50% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

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    98.2
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-89

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is network-reachable without authentication, trivial to exploit, and sits in remote access appliances that are internet-facing by design; CISA flags known use in ransomware campaigns. Attackers typically use this kind of SQL injection to pull user and session data from the device and then log in over the VPN like a legitimate user — an entry point that initially looks benign in logs. Exploitation likelihood is very high, and because the SRA hardware is end-of-life the exposure will not go away on its own. Rate any internet-exposed affected appliance as critical with immediate action; replace internal-only leftovers as high priority.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory: Identify every SonicWall SRA 1600, SRA 4600, SRA VA and SMA 210/410/500v and check firmware. NVD lists all 8.x firmware and 9.0.0.9-26sv or earlier as affected; the CPE data extends the range up to 9.0.0.10-28sv. Treat anything in that range as vulnerable until verified otherwise.
      • Pull end-of-life SRA units off the internet now: No regular fix should be expected for EOL SRA hardware. Block external access to the web portal (typically TCP 443) and the management interface at the perimeter firewall, and move remote access to a supported platform.
      • Update SMA 100 units: Upgrade to the current supported firmware — patch available from the vendor, look up the exact version in the SonicWall PSIRT advisory. Confirm the running version against the advisory after upgrading.
      • Assume credentials are burned: The SQL injection lets an attacker read the appliance database (user accounts, sessions). Reset all local portal and admin passwords plus the AD/LDAP passwords of every account that authenticated through the device; kill active sessions.
      • Enforce MFA on any remote access path before re-enabling it.
      • Preserve evidence: Before reimaging or decommissioning, export config, logs and, where possible, a disk image; if compromise is suspected, check NIS2 reporting duties (24 h early warning).

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Place the appliance in a dedicated DMZ; allow only explicitly required destinations (AD authentication, defined applications), no blanket access to internal networks. Block outbound internet traffic originating from the appliance.
      • Access restriction: Restrict the portal with a source-IP allowlist (partner and site IPs) or put it behind a supported VPN gateway; expose the management interface only to an admin VLAN.
      • WAF/IPS: Front the portal with a reverse proxy/WAF running SQLi signatures (e.g. OWASP CRS at paranoia level ≥ 2); enable Suricata/Snort SQLi rules (UNION SELECT, ' OR 1=1, SLEEP(, hex-encoded strings) on portal traffic.
      • IAM/least privilege: Reduce LDAP bind service accounts used by the appliance to read-only minimum, scope VPN users to required resources via groups, and exclude privileged accounts from remote access entirely.
      • Replacement plan: Log EOL appliances in the risk register with a fixed decommission date; accepting the risk on an internet-facing EOL remote access device is not defensible.

    3. Runbook step 3

      Detection rules

      • Portal/proxy logs: Hunt for requests to the SRA/SMA portal containing SQL metacharacters or keywords in the URI or parameters. SPL sketch: index=proxy dest=<sra_ip> (uri="*UNION*SELECT*" OR uri="*%27*" OR uri="*SLEEP(*" OR uri="*0x*").
      • Suricata/Zeek: On TLS-terminated traffic (WAF/proxy), inspect http.uri and http.request_body for SQLi patterns; alert on unusually large portal responses to unauthenticated requests (data exfiltration).
      • AD authentication: Windows Event ID 4624 (logon type 3/10) and 4768/4769 from the appliance IP or VPN address pool for accounts that don't normally work remotely; bursts of 4625/4771 indicate credential testing. KQL: SecurityEvent | where EventID == 4624 and IpAddress in (vpn_pool) | summarize dcount(Account) by bin(TimeGenerated, 1h).
      • Appliance syslog: Logins from new countries/ASNs, impossible travel, concurrent sessions per account, newly created local admins or config changes.
      • Follow-on activity (EDR): RDP/SMB lateral movement from VPN sessions, execution of psexec.exe, vssadmin.exe delete shadows, wmic shadowcopy, or mass file renames — classic ransomware precursors (Sysmon EID 1, 11).

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Improper neutralization of a SQL Command leading to SQL Injection vulnerability impacting end-of-life Secure Remote Access (SRA) products, specifically the SRA appliances running all 8.x firmware and 9.0.0.9-26sv or earlier

    Source: NVD (NIST), cvelistv5, CISA KEV Catalog

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    SonicWallSonicWall SRA/SMA100
    • 8.x firmware
    • 9.0.0.9-26sv and earlier.
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othersonicwallsma_210_firmware—
    Othersonicwallsma_410_firmware—
    Othersonicwallsma_500v_firmware—
    Othersonicwallsra_1600_firmware—
    Othersonicwallsra_4600_firmware—
    Othersonicwallsra_va_firmware—

    Weakness classes (CWE)

    • CWE-89Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

      Base

      The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.

      Entry at MITRE CWE-89

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

    • psirt.global.sonicwall.comvuln-detail/SNWLID-2021-0017x_refsource_CONFIRM, Vendor advisory
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20028government-resource, US government resource
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